1. Field of the Invention
The field of invention is related to reducing hardware complexity of the display drivers using integer wavelets by adding a few analog multiplexers that are common to a large number of stages (one for each output) in the drivers. A simple controller is implemented in a low-cost complex programmable logic device (CPLD). Further, a large number of gray shades are displayed in RMS (root-mean-square) responding displays by using non-integer wavelets. The technique is demonstrated by displaying thirty-two and sixty-four gray shades in twisted nematic liquid crystal displays (LCD).
2. Description of the Prior Art
Capability to display a large number of gray shades is desirable to increase the number of colors and to avoid gray scale contours in images. A larger number of gray shades can be displayed using amplitude modulation (T. N. Ruckmongathan, Addressing Techniques for RMS Responding LCDs—A Review, Proc. Japan Display '92, pp. 77-80, 1992), successive approximation (K. G. Panikumar and T. N. Ruckmongathan, Displaying Gray Shades in Passive Matrix LCDs Using Successive Approximation, Proceedings of the 7th Asian Symposium on Information Display (ASID-2002), pp. 229-232, 2002) and wavelet (T. N. Ruckmongathan, Nanditha Rao P and Ankita Prasad, Wavelets for Displaying Gray Shades in LCDs, SID 05 Digest, 2005 Society for Information Display International Symposium Digest of Technical papers, pp. 168-171, 2005) techniques. Several addressing techniques for displaying gray shades in RMS (root-mean-square) responding matrix LCDs are reviewed in T. N. Ruckmongathan, “Displaying gray shades in liquid crystal displays”, Pramana Vol. 61, No. 2, pp. 313-329, 2003. A technique to display eight gray shades using wavelets (T. N. Ruckmongathan, Nanditha Rao P and Ankita Prasad, Wavelets for Displaying Gray Shades in LCDs, SID 05 Digest, 2005 Society for Information Display International Symposium Digest of Technical papers, pp. 168-171, 2005) was presented in the Society for Information Display conference as a proof of the concept. A technique to achieve good reduction in hardware complexity of the drive electronics (drivers as well as the controller) when a large number of gray shades are displayed using integer wavelets and other wavelets is described here.